Simulation Of The Radio Propagation In Laboratory House With Applications In Home-Network

As the emergence of the "smart planet", "Sensing China", "wireless city", "Internet of Things" and other concepts, Mobile communications, wireless sensor networks, telemetry and remote control technology have been deep into all aspects of society and life, and play an increasingly important role, such as the rise of ZigBee technology. In the past two years, ZigBee technology has got more and more attention and application. ZigBee technology is mainly used in short-distance communications, remote sensing and perception, especially used in home and office situations. However, these occasions have complex electromagnetic environment and dissemination of conditions, which bring a lot of difficulties to the network design and control of quality of service. And the indoor propagation characteristic of electromagnetic waves is one of the difficulties. This paper studies the indoor wireless channel's transmission model and applications in the home network. After analyzing the features and network topology of ZigBee technology, and researching methods of the indoor channel's electromagnetic calculation and simulation, the ray-tracing method is selected as the main research method. And the simulation software Wireless InSite is used to finish numerical simulation and experiment of wireless communication channel in typical indoor environment. Then, characteristics of wireless transmission channel of the transmitting and receiving modules of telemedicine system based on ZigBee technology are actually measured. Finally this paper gives recommendations of system's actual layout. The main contents of this paper are summarized as below. Firstly, this paper outlines the technology evolution of home network, the necessity of studying indoor wireless communication channel, and the relationship between ZigBee Alliance and IEEE802.15.4.Then, after discussing electromagnetic calculation and simulation research method of indoor communication channel, this paper expatiates on the reason for selecting ray-tracing method, and designs calculation process. Simulation software Wireless InSite, ray-tracing method and the theory of consistency are used to design the simulation experiment of wireless communication channel in typical indoor environment. The simulation results show that when transmitting terminal and receiving terminal is not in the same room, the signals reach the receiving terminal through different paths by reflection, diffraction and transmission, and the loss of diffraction is 3～5dB higher than the loss of reflection, which indicates that we should make full use of the reflection of the wall and metal objects indoor to increase the received signal strength. The signals attenuate rapidly as the increase of distance in Non-Line-of-Sight (NLOS) environments. However, within the distance of 15 meters, the received signal strength can meet the requirement of received sensitivity. In normal environment, the edge distance in a room normally does not exceed 15 meters. Therefore, as the communication module of indoor wireless sensor network, ZigBee can meet the general demand. When the ZigBee receiving terminal is installed in the ceiling, the transmitting terminal should be designed according to the target's height. The higher it is, the better the quality can be. Analysis and experiments prove that, in indoor wireless sensor networks, signal propagation delay is usually in the this context (2×10-8～11×10-8 s). The biggest time difference between the first path and the last path to reach the receiving terminal is 9×10-8s, which does not cause multi-path delay.Finally, the transmitting and receiving modules of telemedicine system based on ZigBee technology are actually measured. Measurement results verify the simulation results well.